Development and application of sub-channel thermal-hydraulic analysis code for liquid metal cooled reactors

The liquid metal reactor, particularly the lead-based fast reactor and the sodium-cooled fast reactor, are widely recognized as the most significant representatives of Gen IV reactors due to their sustainability, economic viability, security, and reliability. To perform thermal-hydraulic safety analyses for liquid metal-cooled fast reactors, adaptive improvements have been made to the models and solution algorithms based on the sub-channel analysis method. As a result, the Sub-channel Analysis Code Of Safety for Liquid Metal cooled Reactor (SACOS-LMR) is developed. The validation of SACOS-LMR was conducted using classic experimental data from liquid metal reactor tests. The results indicate that the dimensionless temperature deviations in the Toshiba 37-pin test were within 10 %, while the coolant temperature errors in the KIT-KALLA 19-pin test were within 5 %, and the rod temperature errors were within 8 %. These findings confirm the accuracy and reliability of SACOS-LMR in predicting the temperature distribution in liquid metal reactors. Additionally, calculations and analyses were performed for the design conditions and hypothetical unprotected loss of flow (ULOF) accident of the ALFRED reactor core, providing valuable guidance for its future design and development.